This week I have been working with a new member who has become frustrated with all the different directions and “interpretations” regarding OSHA’s and EPA’s Maximum Intended Inventory requirements. This is my e-mail response – names and titles have been changed to protect the innocent! (LOL)
I feel your pain, this one small topic has cost the NH3 refrigeration industry millions, and it was a waste of $ when speaking regarding “process safety”!!!
- The WORD document titled “what OSHA says” is correct, but neither of the highlighted areas in that document is referring to the MII requirements. They are relating to EPA RMP and your Quantity reported in your RMP and the way you have to declare the pounds in your WCS.
- Brian’s article is MUCH closer to reality, but even Brian’s article is missing the “intended” part of the Maximum “intended” inventory. Just because my vessel can hold 80% does not mean I have to state that is the MII. He wrote that as a CYA way of establishing your MII so that OSHA/EPA could not take issue with your MII. It is NOT incorrect but is written regarding “compliance” and not true process safety.
- I typically like the work of the XXXXXXXXXX, but in the article you attached, they could not be MORE WRONG. This straightforward sentence flies in the face of true “process safety,” including OSHA/EPA compliance!
“For the purposes of establishing whether or not a given system is a covered process, one needs to determine the “maximum intended system inventory.”
Determining the application of PSM/RMP requirements has ZERO to do with your Maximum Intended Inventory (MII). I mean ZERO! If that were the case, then every process that “could hold” more than the established PSM/RMP Threshold would be covered and that is just NOT factual or sound risk management. This flies in the face of why OSHA and EPA chose the Threshold Methodology to establish PSM/RMP requirements… to get companies to lessen their quantity of the HHC/EHS so to reduce the catastrophic consequences. There are millions of processes that would exceed the threshold if the process was filled to its maximum capability, but the business chose to change the way they manage their inventories and thus no longer have a PSM/RMP covered process.
In ammonia refrigeration, we have to separate MII numbers from the actual “charge” numbers. The “charge number” is used to establish PSM/RMP applicability, and that number needs to match up to our material and energy balance number. In other words, what was the process designed for and that includes how much NH3 does it need to meet that design.
Even though your process may have been built BEFORE 1992, in refrigeration you still have to have these design numbers to refrigerate a space(s) effectively. Someone at some point said we need this space with this much heat generated to be at XXX degrees, this space with this much heat generate to be at XXX degrees, etc. etc. Then refrigeration energy determines how to move that heat (via NH3 as the carrier) to the condensers. Without these numbers, you’re just pissing in the wind! (sorry for my expression). Once the engineer says we need this “size of the process,” then he/she will establish the amount of NH3 necessary to refrigerate those spaces. And hence this is our “charge” number, and if this number exceeds 10,000 pounds, then we have a PSM/RMP covered process.
Then, AFTER the above exercise is completed, we as process safety professionals are tasked with establishing the “Maximum Intended Inventory” (MII) of the PROCESS (not the site) – but each INDIVIDUAL PROCESS (see definition of a process; interconnection and co-location). So if the engineer said we need 30,000 pounds of NH3 to run this process efficiently, then we would begin at 30,000 and merely apply some “rational cushion” and establish our MII at something like 32,000 pounds. We are then BOUND to ensure our “process” (interconnected AND co-located) does not exceed the 32,000 pounds. You may be wondering how could I exceed my MII if I have a process that can handle only 30,000 pounds and I have set my MII at 32,000 pounds. Well already this year, business was found to have installed a skid unit/packaged unit, and the engineer And salesman thought that the best place for this skid unit would be the engine/machinery room (e.g., a room designed to handle NH3). The problem was, they exceeded their self-imposed MII when this additional 3,000 pounds of NH3 was placed inside the engine room. We have seen the same thing with 0ne-ton chlorine cylinders; having too many in the same space (just poor inventory control).
I have seen companies spend upwards of $10,000 to have someone calculate their “charge,” and the calculation was 50,000 pounds! The facility knew they were well over 10,000 pounds but were told they had to have this “charge calculation” to comply with PSM/RMP. That is just hogwash and a snake oil salesman! The only time I would ever recommend a facility spend a dime on having a P.E. stamp their “charge” numbers, would be when they believe they are under the 10,000 pounds and the process was originally designed for more than 10,000 pounds. Due to changes in business, they have shut down 50% of the spaces needing refrigeration and removed NH3 in their attempt to get out of PSM/RMP. Then, and ONLY then, would you be wise to spend $ on having your charge calculated for PSM/RMP compliance reasons? Otherwise, the charge # is more an efficiency # than a safety number; although I always push back on the “charge #” just to be sure my engineer(s) are not being lazy and are actually “managing the inventory” as low as possible.
So again, your “charge” number is for process efficiency AND establishing the application of PSM/RMP. Once you have established the process is a covered process, then we have to establish the MII for that process. This MII # is a “self-imposed” number/quantity, but in the spirit of TRUE PROCESS SAFETY, we need to “justify” this MII number. Much easier in a closed loop process like mechanical refrigeration process vs. a chemical process where raw materials are consumed by the hour and finished product exits the end of the process. In ammonia refrigeration, if your MII # is less than the “charge #” as stated in the material and energy balance number, you will want to have your ducks in a row so you can explain your practicing process safety and not merely OSHA/EPA compliance. But for PSM/RMP, the ONLY time you need to spend $ to establish the “charge #” is when you want to establish your process is BELOW the PSM/RMP TPQ of 10,000 pounds AND your process can contain more than 10,000 pounds safely.
A short story of why MII matters and your ability to justify it. A food facility had a severe fire in 2015 that destroyed 2/3rd’s of the facility. The facility’s charge # was 80,000 pounds for the full facility to operate at its design temperatures. After the fire, the facility moved the production to other facilities and 3rd party tollers. In October 2017, an inspection occurs at the facility and the agency conducting the examination was shocked to find the process holding 80,000 pounds when in fact the refrigeration needs could have been met by 20,000 (calculated by the plant engineer at the request of the inspecting agency). They then determined that the business plan was most likely NOT to rebuild since the other business was able to absorb the work at a reduced price. The final decision had not been made, but for two + years the facility still maintained 80,000 pounds “as designed.” The agency took serious issue with their inability to justify their MII. We have to understand the actual reason for the MII requirement, and you can read about that @ SAFTENG with these two posts:
- Tying your Maximum Intended Inventory back to your material and energy balances
- What is the real reason for Maximum Intended Inventory?
Last but not least, EPA will confuse Tier II quantities with “process quantities,” and this too is BADLY used in error. A facility could have reported 20,000 pounds of ammonia on site in their Tier II’s and NOT have a single PSM/RMP covered process. I know this as I have lived it. The last plant I worked at we had 20,000 pounds of NH3 on site, and the NH3 was in five (5) separate processes which were NOT interconnected, AND they located hundreds of yards from each other (e.g., not co-located). EPA was 100% certain we had a “covered process” based on our Tier II reporting but after a tour of these processes and our PSI documentation they had to agree that NH3 was NOT an RMP chemical for our facility. Luckily, BFGoodrich managed these NH3 processes (ice plants and latent heat plants) as if the processes were PSM/RMP covered, so we even passed the RMP GDC inspection. So understand that EPA inspectors were originally trained to review Tier II reports as a HIGH LEVEL – FIRST PASS to identify “potential” RMP facilities and somewhere along the way, this HIGH LEVEL – FIRST PASS review became a factual piece of evidence that your process is RMP covered. Know YOUR PROCESS BATTERY LIMITS and CONTROL your inventories AND then make sure your smaller operations can NOT be impacted by ANY SINGLE EVENT that could affect over 10,000 pounds of NH3.